011
FXUS63 KGRR 261940
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
340 PM EDT Sat Apr 26 2025

.KEY MESSAGES...

- Frost Tonight

- Thunderstorm Potential Monday Night and Tuesday

- Showers Possible Thursday and Friday

&&

.DISCUSSION...
Issued at 340 PM EDT Sat Apr 26 2025

- Frost Tonight

Ideal set up tonight for cold conditions and some frost formation
as skies clear and sfc high pressure settles directly overhead.
Winds should go light/calm with lows dipping into the mid 30s and
have issued our first Frost Advisory of the new growing season.
This excludes northern sections where the growing season is more
delayed than in the south.

- Thunderstorm Potential Monday Night and Tuesday

Little change from previous thinking. Most likely period for
potentially active weather looks to be later Monday night into
early Tuesday. This is when the remnants of the severe weather
event which occurs to our west on Monday (SPC Moderate Risk) will
be edging this way, aided by a 60 kt low level jet. Possible
MCS/Squall line could be crossing the lake later Monday night and
bring the threat of damaging winds to the lakeshore/wrn sections
for a time before a weakening trend occurs early Tuesday. A re-
firing of strong diurnal storms along the sfc cold front may occur
on Tuesday although recent guidance trends is for the front to
clear our area before that occurs. Also the upper trough is shown
to flatten/deamplify as it comes through MI on Tuesday.

- Showers Possible Thursday and Friday

After a period of sfc and upper ridging on Wednesday a shortwave
trough is shown to eject northeast from the srn Plains while a nrn
stream trough digs south toward the upper Midwest. Surface
boundary south of the state accordingly lifts northward Thursday
and ensemble mean MSLP indicates a sfc low will likely track along
that boundary across srn Lwr MI Thursday evening. Showers and a
few tstms will be likely Thursday/Thursday night, especially over
srn sections, which will be followed by a chance of showers in the
cool cyclonic flow on the back side of the system on Friday.

Weather for next weekend is low confidence at this time with
ensemble guidance suggesting an Omega/blocking pattern developing.
Upper troughs are shown over New England/ern GrtLks and over the
Pacific Northwest with a large upper ridge in between over the
central U.S.. The position of these features will be key for next
weekend`s weather since we could be cool and showery if we`re
part of the New England trough or we could be dry/pleasant if
we`re more under the influence of the upper ridge.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 143 PM EDT Sat Apr 26 2025

What was MVFR cloud cover has now climbed above 3,000 ft and is
scattering out this afternoon. Broken sky conditions may persist
for a few more hours in Mid Michigan including LAN and JXN. Clear
skies are likely tonight with light winds.

&&

.MARINE...
Issued at 340 PM EDT Sat Apr 26 2025

Brisk northerly winds related to a sfc high advancing into the
region from the northwest is creating 3-6 ft waves at this time.
Winds and waves are expected to quickly relax this evening with
sunset with much more tranquil conditions expected on Sunday on Lk
MI as the high settles overhead.

Next period of hazardous winds and waves will commence on Monday
as southerly flow strengthens on the back side of the departing
high, continuing and possibly strengthening further on Monday
night as a cold front approaches from the west. Some potential
exists for a line of strong to svr t-storms to cross Lk MI later
Monday night and this will be followed by a northerly wind shift
Tuesday behind the cold front.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Frost Advisory from 2 AM to 8 AM EDT Sunday for MIZ050>052-
     056>059-064>067-071>074.
MARINE...Small Craft Advisory until 8 PM EDT this evening for LMZ844>849.

&&

$$

DISCUSSION...Meade
AVIATION...CAS
MARINE...Meade